Method and apparatus for curing UV varnishes

Abstract

The present invention relates to a method for curing a UV varnish (3) applied to the surface of a substrate (2) using a roller (7), the roller core (8) of which carries at least one UV radiation-emitting UV source (10), in which UV radiation penetrates the surrounding roller coating (9) and strikes the surface coated with the UV varnish (3).

Description

[Technical Field]

[0001] The present invention relates to a method for curing UV varnishes using rollers and an apparatus therefor. [Background technology]

[0002] In varnish or lacquer technology, the curing of varnishes using ultraviolet (UV) radiation is becoming increasingly important. UV-curable varnish systems, hereinafter also referred to as UV varnishes, have relatively high mechanical and chemical resistance and can be cured relatively quickly, for example within a few seconds. Furthermore, the energy required for curing in UV-curable varnish systems is significantly lower than that required for thermally curable varnish systems, and UV-curable varnish systems can be easily formulated without solvents.

[0003] Due to these properties, UV varnishes have begun to make great strides, for example, in the furniture industry and in web-type substrates or components. UV varnishes are also increasingly being used to coat metals.

[0004] Since uniform irradiation by UV light is very advantageous for the curing of UV varnishes, their use is currently substantially limited to the coating of flat substrates and / or substrates with relatively simple geometries. The substrates or components may be, for example, sheets or panels made of metal, wood, stone, cardboard, or other materials to be coated.

[0005] When a UV varnish cures, the UV light splits the photoinitiator in the UV varnish into radicals, which in turn polymerize the double bonds in a chain reaction. The reaction proceeds rapidly, but is interrupted at the interface with the ambient air by oxygen molecules, which act as radical scavengers. To counter this, relatively strong doses of UV light and photoinitiator are used so that the varnish is sufficiently crosslinked and "tack-free" even on the surface.

[0006] Mercury vapor lamps are often used as UV sources, and their spectrum can be adapted to requirements by doping. Electron beam and X-ray equipment have not been widely adopted due to occupational health reasons and high acquisition costs. For many years, UV LED emitters, which have low energy requirements and operate without mercury, have also been used. UV LED emitters produce UV light with longer wavelengths, but have the disadvantage that oxygen inhibition is now a problem. Only reactive varnish systems can be cured with LED emitters, or the cure takes place under inert gas or at very short distances.

[0007] In particular, it would be highly advantageous to widely switch curing processes from mercury vapor lamps to LED emitters, given the potential for energy savings. Mercury vapor lamps generate a broad spectrum of electromagnetic radiation, only a small portion of which is needed to activate the photoinitiator. LED emitters can more selectively generate radiation at desired wavelengths. While conventional curing processes often require 100 to 200 watts per centimeter of lamp length, with LED lamps, 4 to 8 watts of radiation per centimeter may be sufficient. This is especially true when the curing reaction can be carried out in the absence of oxygen. For a curing system with a typical working width of 130 cm, the energy requirements are 13 to 26 kW using conventional lamp technology. In an example, the energy requirement for generating radiation may be 0.5 to 1 kW.

[0008] DE 10 2013 215 739 A1 and GB 2 576 922 A each disclose a roller formed by a rotatable, transparent hollow cylinder inside which the actual light source is fixed.

[0009] German Patent No. 101 44 579 (C2) discloses a method for producing microstructures and / or complex microsystems from microstructures by layer-by-layer construction in and from a photocurable liquid between two interfaces, where the individual layers are formed by exposing the liquid through a mask corresponding to the layer topography, and the distance between the interfaces successively increases by the respective layer thickness, as well as an apparatus for implementing this method. The individual layers of the structure to be constructed are produced between two opposing, counter-rotating rollers of a roller pair that form the interface, the roller spacing of each roller pair being determined by the thickness of the layer to be formed and the thickness of the pre-existing layer, and the first layer is applied to a substrate carrier film passing between the rollers. Each roller of the pair is designed as an exposure roller and is made of a material transparent to electromagnetic waves, on which an electromagnetic wave emitting source in the form of a light source is arranged, the surface of the exposure roller being non-adhesive. In particular, the arrangement of the light source on the rotating exposure roller makes it relatively complicated to implement in practice.

[0010] Furthermore, EP 1667836 B1 describes a tool and method for generating microstructured surfaces, including a die having a negative of the microstructure to be generated and a pressure roller that can move over the surface to press the die against the surface. The die is arranged for rolling movement between the roller and the surface, with the negative of the die facing the surface as the roller moves over the surface. An apparatus for promoting the curing of a curable material, including a light source and / or heat source for irradiating and / or heating the microstructureable surface, is arranged so that as the pressure roller moves over the surface, the apparatus accompanies the movement of the roller and acts on a portion of the surface. The light source and / or heat source is located inside the pressure roller and is mounted so that the energy emitted by the light source and / or heat source can be transmitted through the pressure roller material to the die (in the case of heat) or radiated through the die (in the case of light). In the latter case, the roller material must have a high transmittance for the wavelengths emitted by the light source.

[0011] EP 1951436 B1 discloses a "calendering process" in which a film is hardened through to produce a structured surface, where the problem is the edge area of ​​the coated plate, which must be trimmed. Summary of the Invention

[0012] The present invention addresses the problem of creating a method and apparatus of the type mentioned at the outset that ensures reliable curing of a UV varnish on a substrate at a relatively low equipment cost.

[0013] According to the invention, this object is achieved by means of the features of the independent claims.

[0014] The dependent claims present advantageous embodiments of the invention.

[0015] In a method of curing a UV varnish applied to the surface of a substrate using a roller, the roller core holds at least one UV radiation emitting source, and UV radiation penetrates the roller coating surrounding the outer periphery and strikes the surface coated with the UV varnish.

[0016] An apparatus for carrying out this method comprises a roller with a central roller core and a peripheral roller coating, the roller core carrying a plurality of UV sources distributed around its circumference, the emitted UV radiation of which penetrates the roller coating, which is transparent to UV radiation, and impinges on the surface of the substrate coated with the UV varnish to cure the UV varnish.

[0017] In the first step, the UV varnish is applied to the substrate or component surface. This coating can be carried out in one or more steps by rolling, casting, spraying, using a doctor blade or similar. The substrate is conveyed or transported using a suitable transport device. For example, a roller or a counter roller arranged opposite the roller can be driven to transport the substrate. The direction of movement of the substrate and the roller can be the same, and the speeds of the substrate and the roller can be the same or different.

[0018] Due to the contact pressure of the roller or roller coating on the surface of the substrate, the roller coating forms a surface parallel to the substrate, the so-called roller nip, along its rolling line. Initially, uncured UV varnish is located between the substrate and the roller coating. Small beads of liquid UV varnish form at the inlet edge between the substrate and the roller coating and grow until the amount of varnish delivered with the substrate corresponds to the amount of varnish transported under the surface of the roller coating. The size of the resulting varnish beads depends substantially on the viscosity of the UV varnish, the contact pressure of the roller or roller coating on the surface of the substrate, and the velocity gradient between the roller and the substrate. In addition, the characteristics of the roller coating and the substrate affect bead formation.

[0019] The UV varnish located between the substrate and the roller coating is cured with UV radiation during the transport of the substrate. For this purpose, a UV radiation source or UV radiation is aligned with the roller core and preferably attached to its outer circumferential surface so that the UV radiation penetrates the roller coating and strikes the UV varnish to cure it. Of course, without departing from the scope of the present invention, optical elements can be arranged to focus or direct the UV radiation emitted from the UV source, and these optical elements can be assigned to the roller core and / or the roller coating.

[0020] Because the curing process is carried out without contact with oxygen from the ambient air, i.e., without oxygen inhibition, the degree of crosslinking on the surface is relatively high, thereby achieving favorable mechanical and chemical properties of the varnish surface. After UV-induced polymerization, the workpiece, i.e., the substrate with the cured varnish, is released again by conveyance, thus leaving the area of ​​the roller. A small amount of excess varnish accumulated on the sides of the substrate edge and in the direction of travel of the runout edge remains attached to the workpiece as a burr. Upon return of the roller coating, the varnish is relatively easily separated from the roller surface. This is supported by the selection of a suitable coating material (e.g., silicone with an E coefficient of approximately 8 MPa) and, if necessary, by surface treatment of the roller. If a high-quality optical and highly uniform surface structure is to be achieved on the substrate, it is important that the cured varnish material does not adhere to the roller. If necessary, a scraper can be provided to remove such adhering varnish residue from the roller coating.

[0021] Currently available LED emitters with radiation in the 365-390 nm spectral range can be used as UV sources. Other wavelength ranges are also possible. At 365-390 nm, this radiation penetrates relatively deeply into the cured varnish material. A skilled artisan will select a suitable emitter depending on the UV varnish formulation. The LED UV emitters are advantageously distributed over the length and circumference of the roller core.

[0022] When coating rigid plate-like materials, the method described herein has the advantage that a uniform pressure is applied to the polymerization mixture, i.e., UV varnish, over the entire width of the roller, and there is no "slippage" of the film in the edge areas, which would lead to defects there, so that defects in the edge areas, which are common in methods using, for example, calendering processes known from the prior art, do not occur or at least are reduced in extent.

[0023] The roller core must be mechanically stable enough to tolerate the contact pressure on the opposing roller or conveyor belt and absorb the force required to rotate the roller. Furthermore, the roller core should advantageously have reflective properties to reflect scattered light back onto the roller surface, i.e., the surface of the roller coating. The roller core can be made from metals such as iron, steel, aluminum, or metal alloys such as brass. For more pressure-sensitive substrates and small rollers, plastics can also be used to make the roller core.

[0024] The roller coating should have good transparency to the UV radiation required to initiate the polymerization reaction. A low optical density of the material can be beneficial, since radiation transfer from the roller coating to the polymerization mixture can be advantageous when carried out in a medium with a high optical density. In addition, the roller coating must have a certain elasticity to allow the formation of a roller nip under which the crosslinking reaction can occur. Good mechanical deformability and rapid recovery to the original shape are also advantageous to facilitate the separation of the cured varnish from the roller surface. Adhesion of varnish material to the roller leads to a deterioration in the quality of the coating.

[0025] The UV emitters can be placed as an intermediate layer between the roller core and the roller coating. They can also be integrated into the roller core or into the roller coating. The UV emitters should be distributed as uniformly as possible across both the circumference and width of the roller. If a non-uniform radiation distribution is required for technical reasons, deviations from this specification are permitted.

[0026] In these designs, the UV emitters or UV sources are switchable and are only supplied with voltage when the emitted radiation takes a direct path from the UV emitter through the roller coating to the polymerization mixture located under the roller nip. For position-dependent voltage supply, an electronic controller switches the voltage supply of a particular UV source on and off depending on a signal from a position detection sensor, or the current paths of interconnected UV sources arranged in a row are connected to contacts assigned to the end faces of the roller, which act on voltage-carrying contact segments to open or close an electrical circuit.

[0027] Preferably, the array of UV sources extending across the width of the roller core is integrated into light segments that can be replaceably mounted on the roller core. After reaching the end of their useful life or if they are otherwise damaged, the individual light segments can be replaced, especially after the roller coating has been removed.

[0028] To dissipate the process heat, cooling devices are assigned to the rollers: for example, the roller core may have cooling holes or the like through which a coolant flows.

[0029] Preferably, the roller coating is elastic. Depending on the contact pressure of the roller against the UV varnish-coated substrate, a larger or smaller contact area is formed. Ideally, the roller coating has a Shore A hardness of 30 to 60. Therefore, the roller coating is designed to be relatively soft. Furthermore, the roller coating can be arranged on the roller core in an exchangeable, particularly reversible, manner. This means that different structures of the cured UV varnish can be created using different roller coatings, and when the roller coating wears out, it can be replaced. To create surface effects on the varnished surface, the roller coating can be smooth or have a surface structure. The surface characteristics of the roller coating are used to create the surface structure of the varnish coating, as the surface structure of the roller is reflected in the varnish surface. For example, a smooth surface of the roller coating can create a high-gloss surface on the finished part, i.e., the coating or UV varnish, while depending on the surface structure, effects such as different degrees of gloss, structure, or fingerprint resistance can be achieved.

[0030] The roller coating may have a thickness of 2% to 80% of the radius of the roller, preferably 10% to 20%.

[0031] To transport the substrate and determine the thickness of the UV varnish layer on the substrate, an adjustable counter-roller is assigned to the roller, allowing the UV varnish-coated substrate to be transported between the roller and the counter-roller. Of course, the roller and the counter-roller are mounted in a frame and, if necessary, connected to a drive that allows both rotational and linear movement of the counter-roller relative to the roller. The counter-roller ensures that the UV varnish-coated substrate is pressed against the roller with the required pressure. The distance between the substrate and the roller must be set so that the distance between the coated roller and the unloaded roller is at least 1% of the thickness of the roller coating and at most 20% of the thickness of the roller coating, preferably 3% to 10% of the thickness of the roller coating.

[0032] The pressure of the roller is distributed evenly over the entire surface of the substrate, and even the edge areas do not separate from the substrate, which reduces the risk of defects on the varnished surface. Furthermore, there is no need to remove defective edge areas. Therefore, substrates that have already been trimmed can be coated.

[0033] The edges, or at least the curved edges, are minimally coated by pressing in a hardening roller. This offers advantages when coating panels with glued edges, which are often used in the furniture industry. Since the glued seam is sealed from above with a top coat, workpieces varnished in this way are much better protected against moisture penetration. Any protruding burrs of coating material on the vertical edges can be easily removed mechanically using a device.

[0034] For convenience, the UV source is designed as an LED UV emitter, which is energy efficient and ensures that the system generates relatively little heat. Of course, other radiation sources for the UV light can be used without departing from the scope of the present invention.

[0035] Furthermore, for deep curing or post-crosslinking of the UV varnish, a light source is provided which emits actinic radiation, which can be directed onto a substrate coated with the surface-cured UV varnish.

[0036] When the UV source or LED UV emitter is located on the surface of the roller, i.e., on the outer periphery of the roller core directly beneath the roller coating, most of the radiation is directed toward the UV varnish to be cured, and the loss of intensity is relatively low compared to rod-shaped or point-shaped radiation sources mounted in the center of the roller. Furthermore, heat is dissipated from the UV source through the roller core, and each UV source is active only for a specific period of time while it is positioned so that its radiation strikes the UV varnish, and can cool during the remaining inactive period. Because the radiation sources can be mounted relatively close to the roller surface, any roller circumference is possible.

[0037] It will be understood that the features set out above and further described below can be used not only in the respective combinations specified but also in other combinations, the scope of the present invention being defined solely by the claims. [Brief explanation of the drawings]

[0038] The invention will now be explained in more detail on the basis of exemplary embodiments with reference to the associated drawings.

[0039] The drawings are as follows: [Figure 1] 1 is a schematic diagram of an apparatus for coating the surface of a substrate with a UV varnish, i.e., for carrying out a varnish process. [Figure 2] 2 is a schematic side view of an alternative roller according to detail II of FIG. 1; [Figure 3] FIG. 3 is a schematic perspective view of the roller according to FIG. 2; [Figure 4] 3 is a further side view of the roller according to FIG. 2; [Figure 5] FIG. 5 is a schematic front view of the roller according to FIG. [Figure 6]3 is a further side view of the roller according to FIG. 2; DETAILED DESCRIPTION OF THE INVENTION

[0040] The apparatus essentially comprises a conveyor belt 1, which may also be replaced by one or more opposing rollers, serving to support and transport a substrate 2, which is essentially a plate- or belt-like component or workpiece, the surface of which is to be coated with a UV varnish 3. In a first step, the UV varnish 3 is applied from a storage container 6 to the surface of the substrate 2 in a coating station 4 by means of a rotating coating roller 5.

[0041] In a second step, the UV varnish 3 is cured using UV radiation. For this purpose, the roller core 8 of the roller 7, which further comprises a peripheral roller coating 9 that is transparent to UV radiation, is equipped with a UV source 10 designed as an LED UV emitter 11.

[0042] In a third step, the UV varnish 3 cured on the surface of the substrate 2 is deep-cured using a conventional emitter 12, which in this case can be designed as an energy-saving LED emitter 13 with radiation in the spectral range of 365 nm to 390 nm. This deep curing is not necessary in all cases and depends on the UV source 10 used, the UV varnish 3 used, and other manufacturing or process parameters, such as the process speed in particular.

[0043] The LED UV emitters 11 may be distributed around the periphery of the roller core 8 of the roller 7, for example extending in a mesh pattern over the peripheral surface as shown in FIGS.

[0044] Alternatively, the UV source 10, designed as an LED UV emitter 11, can be inserted into a groove-like recess 16 extending around the roller core 8 and across the width of the roller 7. The recess 16 may have a reflective surface and a geometric shape that focuses the UV radiation, as shown in FIGS. 2 and 3. In this case, the LED UV emitter 11 can be integrated, for example, into a casting compound, which can be combined to form light segments 17 that are replaceably fixed in the associated recess 16. The channel-like recess 16 can be filled with various media, such as liquids or gases. These media should be as transparent as possible to UV radiation and have an advantageous optical density. In addition, the medium can act as a heat carrier and dissipate unwanted process heat.

[0045] If the LED UV emitter 11 is located on the surface of the roller core 8 or in a recess 16 of the roller core 8, the heat generated during radiation emission can be dissipated through the backside of the LED UV emitter 11 and through the medium present in the metal roller core 8 or recess 16. The roller core 8 can also be provided with cooling holes for a water cooling system, which is coupled to a cooling device in a manner well known to those skilled in the art. By dissipating the heat from the LED UV emitter 11, heating of the LED UV emitter 11, which would lead to functional limitations, can be avoided, and a relatively high radiation output or a low wavelength of UV radiation can also be achieved, with the lower wavelength being advantageous due to the higher energy content when curing the UV varnish 3.

[0046] The coolant flows through an annular line 18 which is sealed against the roller 7 by end face slip ring seals 19 to provide an inlet and an outlet, as shown in FIGS.

[0047] Control of the UV source 10 is advantageously performed by an arrangement of voltage-carrying contact segments 20, shown in Figure 6, which are supplied with voltage only when aligned with the substrate 2, i.e., when a relatively direct radiation path is provided, and which are acted upon by an electronic controller capable of detecting the position, or by contacts 21 assigned to the LED UV emitter 11 or the light segment 17, to close an electrical circuit depending on the rotational position of the roller 7. To supply energy to the LED UV emitter 11, an electrical circuit is closed only when the light segment 17 is located in the area of ​​the arc-shaped contact segment 20 with the associated contact 21. This allows the LED UV emitter 11 to be switched on and off sequentially, saving electrical energy and reducing heat generation.

[0048] The UV radiation-transmitting roller coating 9 of the roller 7 has a thickness of about 2% to 80%, preferably 10% to 20%, of the radius of the roller 7, and has elasticity with a hardness of, for example, 30 to 60 Shore A.

[0049] The roller coating 9 can be made of various materials that are transparent to UV radiation, and advantageously have a low absorption coefficient in order to achieve high radiant intensity. For example, elastomeric polyurethane materials, silicone rubber, or other transparent elastomeric rubbers can be used, which preferably do not contain any fillers that would increase the absorption coefficient.

[0050] The LED UV emitters 11 assigned to the roller core 8 can be directly surrounded by the roller coating 9. The beam path can then pass directly from the LED UV emitters 11 to the roller coating 9 without any additional material transfer. This structure can be easily realized by fixing the LED UV emitters 11 to the roller core 8 and pouring the roller coating 9 around them.

[0051] Alternatively, the roller coating 9 made of a silicone rubber mixture can be applied to the roller core 8 in multiple layers, for example by applying a relatively elastic layer with very good adhesion to the roller core 8 during the coating process, and then the pre-coated roller 7 is transferred to a casting mold and cast with a type in which the majority of the silicone rubber has advantageous mechanical properties in terms of elasticity and durability. To minimize adhesion of the UV varnish 3 to the roller coating 9, the roller coating 9 can be subjected to a surface treatment or a release agent can be used during the manufacture of the roller 7.

[0052] In a further alternative embodiment, the roller coating 9 can also be made to be fully or partially replaceable. This means that different surface structures can be created as needed without having to have different rollers 7 available. In addition, worn roller coatings 9 can be replaced without having to manufacture an entirely new roller 7.

[0053] The roller coating 9 can be formed in such a way that after its removal, the individual LED UV emitters 11 or light segments 17 remain accessible, allowing for replacement if necessary. The roller coating 9 can, for example, be formed as a kind of cover that can be pressed onto the roller core 8. Axial fixation of the roller coating 9 can preferably be achieved on the end face of the roller 7 using a suitable holder. For radial fixation, the roller coating 9 can be provided with protrusions or extensions that engage in corresponding recesses in the roller core 8. When the roller coating 9 is pulled onto the roller core 8, it can be elastically stretched, so that it also rests pretensioned against the roller core 8.

[0054] Of course, the roller coating 9 can be provided with a structure on its peripheral surface 14 that is produced by subsequent treatment or by a casting process in which the structure of the die is incorporated into the casting mold.

[0055] For optimal functioning of the system, the highest possible radiation intensity during the curing of the UV varnish 3 is advantageous, in order to allow a high processing speed and / or low reactivity of the UV varnish 3. For this purpose, it is advantageous if the radiation of the UV source 10 is focused with optical components in order to avoid unproductive scattered light.

[0056] To cure the UV varnish 3, any type of electromagnetic radiation suitable for activating a photoinitiator or initiating a radical reaction through a separate process can be used. Care must be taken to ensure that the radiation is not absorbed by the roller coating 9. The feed speed of the substrate 2 is 5 or 10 m / min. Good curing of the UV varnish 3 is achieved. The edge areas of the substrate 2 have good optical quality. No unwinding of the roller is observed, and subsequent post-curing is not absolutely necessary.

[0057] The UV Varnish 3 used contains polyether acrylate as the reactive resin component, resulting in a high-quality, light-resistant varnish for indoor use. TMPO3TA is used as the reactive diluent, which is advantageous in terms of labeling. TPO-L is used as the photoinitiator, which functions very well at the wavelength of radiation used. Airex 901W is used as the defoamer, and Tego Rad 2650 is used as the leveling agent.

[0058] The following recipes are based on 100T. 75 T Laromer PO 84 F(BASF) 19.5 TMPO3TA (e.g., Miwon) 5T TPO-L (BASF) 0.3 T Tego RAD 2650 (Evonik) 0.2T Tego Airex 901W(Evonik)

[0059] The formulations shown are examples only, many other combinations are possible depending on the coating requirements. [Explanation of symbols]

[0060] 1. Conveyor belt 2. Base material 3.UV varnish 4. Coating station 5.Coating roller 6.Storage container 7. Laura 8. Roller Core 9. Roller coating 10.UV source 11. LED UV emitter 12. Emitter 13. LED emitter 14.9 Surface 15. Components 16. Recess 17. Optical Segment 18. Line 19. Slip ring seal 20. Contact Segment 21. Contact

Claims

1. 1. A method for curing a UV varnish (3) applied to the surface of a substrate (2) using a roller (7), characterized in that the roller core (8) carries at least one UV radiation emitting source (10) so that UV radiation penetrates the surrounding roller coating (9) and strikes the surface coated with the UV varnish (3).

2. 2. The method according to claim 1, characterized in that the voltage supply of the at least one UV source (10) is position-dependent on the orientation of the at least one UV source (10) relative to the substrate (2).

3. 3. A method according to claim 1 or 2, characterized in that the roller (7) is unrolled against the substrate (2).

4. 4. The method according to any one of claims 1 to 3, characterized in that the substrate (2) is conveyed between the roller (7) and a counter roller or conveyor belt (1) opposite the roller (7).

5. 5. The method according to any one of claims 1 to 4, characterized in that the UV varnish (3) cured on the surface of the substrate (2) is subsequently deep-cured using a conventional emitter.

6. 10. An apparatus for carrying out the method according to claim 1 using a roller (7), comprising a central roller core (8) and a peripheral roller coating (9), characterized in that the roller core (8) carries a plurality of UV sources (10) distributed over its periphery, the emitted UV radiation of which penetrates the roller coating (9), which is transparent to UV radiation, and impinges on the surface of the substrate (2) coated with the UV varnish (3) in order to cure the UV varnish (3).

7. 7. Apparatus according to claim 6, characterized in that the UV source (10) is linearly oriented and extends across the width of the roller core (8).

8. 8. Apparatus according to claim 7, characterized in that a plurality of UV sources (10) arranged in a row can supply a voltage depending on the position of the plurality of UV sources (10) relative to the substrate (2).

9. 9. The device according to claim 8, characterized in that for the position-dependent voltage supply, an electronic controller switches on and off the voltage supply of a particular UV source (10) depending on a signal from a position detection sensor, or the current paths of the interconnected UV sources (10) arranged in a row are connected to contacts (21) assigned to the end faces of the rollers (7), which contacts act on voltage-carrying contact segments (20) to open or close an electric circuit.

10. 10. The device according to any one of claims 6 to 9, characterized in that the row of UV sources (10) extending across the width of the roller core (8) is integrated with light segments (17) that can be replaceably mounted on the roller core (8).

11. Apparatus according to any one of claims 6 to 10, characterized in that a cooling device is associated with said roller (7).

12. 7. Device according to claim 6, characterized in that the roller coating (9) of the roller (7) is elastic.

13. 13. Apparatus according to any one of claims 6 to 12, characterized in that the roller (7) is assigned to a counter roller or conveyor belt (1), and the roller (7) and / or the counter roller and / or the conveyor belt (1) are adjustable relative to one another, so that the substrate (2) coated with the UV varnish (3) can be transported between the roller (7) and the counter roller or the conveyor belt.

14. 7. Device according to claim 6, characterized in that the UV source (10) is designed as an LED UV emitter (11).

Images